Fuse plug



March 25 1924. 1,488,420

w. WATTS FUSE PLUG 25 Filed 16, 1.922

\LZ/ x 'ks VVVV WITNESSES INVENTOR I WEI/liar Wait-S $22M ATTORNEYS i To all wlwmit Patehted Mar. 25, 1924.

PATENT OFFICE.

WALKER} WATTS, OI NEW YORK, 11'. Y.

FUSE PLUG.

Application am February 18, 19 22. Serial No. 581,045.

comem: Be it known t at I, War/ran WATIB, a subject of the King of Great Britain, and a resident of the cit of New York, borough of Manhattan, in the county and State of New York, have invented 'a new and Improved Fuse Plug, of which the following is a full, clear, and exact description.

The present invention relates to an improvement in fuse plugs and seeks as its rincipal object to provide a. fuse plug which includes a holder and a detachab e fuse element whereby the latter may be renewed when fused in order to effect economy by saving of the holder.

At the present time it is the common practice to discard the holder when the fuse element has been fused. Furthermore in the 1 present construction of fuse plugs considerable difiiculty is experienced in detecting whether or not the fuse element has been fused, thus requiring considerable time in testin of the various plugs.

In t e present invention the fuse element is constructed in such a manner as to dispose its weakest point in a position to be readil observed whereb when fused the necessity of testing is obviated.

As a further object the invention contem lates a fuse plug construction which ren ers the removal or association of the fuse element with its holder a simple operation and which precludes the necessity of removin the base of the plug from the socket of in replacing or removing said fuse element.

As a further object the invention aims to provide a positive means for effecting the engagement of the extremities of the fuse element with the contact elements of the plug whereby arcing due to a loose fit is reduced to a minimum.

With the above recited and other objects in view, the invention resides in the novel construction set forth in the following specification, particularl pointed out in the appended claims and i lustrated in the accompanyin drawings, it being understood that the-ri t is reserved to embodiments other than t ose actually illustrated herein to the full extent indicated by the ing of the terms in which tie claims are ex ressed.

n the drawing- Figure 1 is a collective sectional view i1- I rial such as porcelain which is provided with the instrument board or fuse box neral meanlust-rating the cap or head of the fuse plug remoyed from the base.

- Flg. 2 is a side elevation of the base with the cap or head associated therewith and illustrating the latter in section, said section being taken approximately at a right angle to Fig. '1.

Fig. 3 is a plan view of the base.

4 is a similar view of the cap or head. F 1g. 5 is a plan view of the fuse element prior to its association with the holder.

Referring to the drawings by characters of reference the fuse plug consists of a base 10 preferably constructed of insulating matea threaded extension 11 having a metallic .peripheral shell 12 which constitutes a shell contact for connectin the spring terminal 13 with a source of e ectrical energy when the plug is inserted in a socket. A central metallic stud 14 is arranged axially of the extension 11 and is electrically connected to the opposite spring terminal 15. The spring terminals 13 and 15 are arranged within the diametrically opposed sockets 16 of the plug base and said base is provided at its up er surface With a transverse rib 17 concaved as at 18t0provide the spaced upstanding supporting lugs 19 upon which the fuse element 20 is supported at its opposite ends. The head or cap 21 of the fuse plug is provided on its under side with a transverse recess 22 with which a superposed recess 23 ofa lesser length communicates to provide shoulders 24. The recess 23 further communicates with a sight opening 25 extendin through the u per wall of the cap or hea which is close by means of a transparent panel 26 preferably of mica. The cap is provided with a pair of diametrically disposed depending contact legs 27 which are desi nod to be received within the sockets 16 o the base and which are adapted to be frictionally engaged by the spring contacts 13 and 15 to retain the ca against casual displacement or separation rom the base. The contact legs 27 are each provided with an arcuate extension 28 the free extremities 29 of which are respectively disposed withinthe recess 22 at the opposite ends thereof. The legs 27 and extensions 28 are of a conducting material whereby when the plug is inserted in a socket the current will flow from the stud 14.- to the spring contact 15, thence throu h the contact] leg 27 to one extremity of t e extension 28, through the fuse element 20 to the opposite extremity 29 of the opposite extension 28, the leg 27, the spring contact 13, thence to the shell contact 12. The fuse element 20 consists of a strip of fusible material. of rectangular formation which is provided in its opposite longitudinal edges with arcuate cutaway portions 30 to provide enlarged opposite extremities which are joined by a central portion of gradually decreasing width and strength toward the central portion thereof. In use the fusible element 20 is supported at its opposite ends by the lugs 19 and the cap 21 is associated with the base 10 by inserting the legs 27 in the sockets 16, thereby im inging and clamping the opposite ends of the fusible element between the extremities 29 and the outer sides of the lugs 19 or the rib 17 to establish electrical communication from the circuit wires through said fusible element. The arrangement and association of the fusible element with the holder disposes the weakest or narrowest portion of the same in direct alignment with the sight opening 25 whereby the condition of said fusible element will be readily apparent to the observer. Under this arrangement the necessity of testing the various plugs to detect the fused plug is obviated as the fusible element is bound to fuse at a point where it can be readily observed. Furthermore when the fuse element becomes fused it may be readily replaced at a small expense by removing the cap or head 21 and inserting a new element and this without the necessity of removing the base from the fuse box socket. It should be further noted that the construction and arrangement insures at all times a close contact of the extremities of the fuse element with the contact members, thus eliminating any possibility of arcing. The removal or insertion of the plug as a whole may be accomplished in the usual manner and the common practice of discarding the holder or entire plug when the fusible element is destroyed is eliminated, thus effecting economy.

I claim:

1. In a fuse plug, a plug bod havin diametrically disposed sockets and space lugs projecting from one end, insulated terminal contacts on the opposite end, 5 ring contact fingers arranged within the soc ets and connected to said terminal contacts, a detachable head having a recess for the reception of the lugs, spaced contact le s adapted to enter the sockets and frictionally engage the spring finger contacts for retainin the head in associated relation with the pug body, said legs having extensions respectively arranged in the o posite ends of the recess, and a detachab e fuse element positioned over the lugs with its opposite ends in clamping engagement between the leg extensions at the end of the recess and the outer sides of the lugs to establish electrical communication with the plug terminal contacts.

2. A fuse plug comprising a plug body of insulating material having a threaded extension, a threaded shell fitted over said extension, a central contact terminal extending therethrou h, a pair of sockets in the opposite end of the plug body, spring contact fingers connected respectivel to the shell and the central terminal, a pair of hi projecting from the socheted end of the plug body, a head having a recess in the end confronting the plug body for the reception of the lugs, contact legs projecting therefrom and insertable within the sockets for frictional engagement with the spring fingers, extensions from said legs arranged within the opposite ends of the recess, a fuse ele- -ment positioned over said lugs and clamped at its 0 posite extremity between the extensions 0 said legs and the outer side of the lugs.

WALTER WATTS. 

